In the year 1989 some of the West Siang district’s territory was given to the East Siang district. Since 1999, this particular territory has been under the new Upper Siang district. Some archaeologically significant items that found out from the Malinithan site in West Siang are on displayed at the Jawaharlal Nehru Museum in Itanagar. At present West siang is divided into two parts namely upper siang and lower siang.
Geographically, the district has a total area of 5,212 sq. km. and occupies the rank 8th in State and 207th in India on the bases of this size. It lies at 28015'N latitude, 94075'E longitude and 578 m altitude. In the year 2019, there was a total 87.67% forest area of total geographical area. The district is bounded by China and Upper Siang District, Arunachal Pradesh in the North and North East, Assam in the South, East Siang District, Arunachal Pradesh in the South East and Upper Subansiri District, Arunachal Pradesh in the West. The principal rivers that flow through the district are Yomgo or Siyom, Sirit, Yangyapchu, Rimi, Sike, Shiet, Hiru, Siji, Sigen and Hirik. The climate of the district remains pleasant almost throughout the year. Most of its rainfall occurs in the monsoon season. The actual rainfall in the district was 2144.8 mm in the year of 2018-19.
Administratively, the district is divided into 21 sub-districts, 2 towns and 461 villages. English is its administrative language. It has administrative headquarters located at Along Town, situated at the distance of 304 kms from the State Capital. There are seven legislative assembly constituencies in the district namely Liromoba, Likabali, Basar, Along West, Along East, Rumgong, and Mechuka. The first six are the part of Arunachal West Lok Sabha constituency whereas Mechuka is the part of Arunachal East Lok Sabha constituency.
Demographically, according to the 2011 census, the district has a total number of 20,474 households with a total population of 1,12,274 comprising 58,168 are males and 54,106 are females which leads it to rank 4th in the state and 612 in India. The density of population of the district is 22 (persons per sq km.). The sex ratio is pegged at 930 (females per 1000 males) while the child ratio stands at 941 (females per 1000 males). As per 2011 census the percentage of major religions practiced by the people of the district are Christian and Hindu with 26.69% and 14.14% of the total population. The population growth rate during the period of 2001-2011 was 8.04% including 7.03% were males and 9.15% were females. According to 2011 census the principal language in the district is Adi with 78.64%. In the year 2017 the number of live births in the district was 9,219 out of which 4,524 were males and 4,695 were females. In the same year the number of deaths in the district was 245 out of which 179 were males and 66 were females.
The district is mainly dependent on agricultural sector. More than half of its populations are engaged in agriculture in order to earn their livelihood. The district is famous for its high quality of paddy and rice. Some other major agricultural products in the district are maize, millet, ginger, potato, chili, ladies finger, cabbage, arum, etc. natives of the district earn their extra income from some horticultural products like orange, pineapple, pears, banana, guava, plum, papaya, litchi, walnut, cardamom, black pepper, apple, etc. The district is also rich in mineral resources such as coal, graphite, limestone, marble, clay, ferrous, ochre, sulphur minerals, etc. The GDDP or Gross District Domestic Product during 2007-08 was Rs. 53,365 lakh at Current Price and Rs. 23,604 lakh at Constant Prices during 1999-2000. The NDDP or Net District Domestic Product during 2007-08 was Rs. 27,853 lakh at Current Price and Rs. 21,089 lakh at Constant Prices during 1999-2000. The Per Capita Income or NDDP, at factor cost during 2007-08 was Rs. 24,518 at Current Price and Rs. 1,136 at Constant Prices during 1999-2000.
Education wise, according to the 2011 census, the district has a literacy rate of 66.46% including 72.81% are males and 59.63% are females. The total number of literates in the district is 64,746 comprising 36,777 are males and 27,969 are females. The total number of illiterates in the district is 47,528 comprising 21,391 are males and 26,137 are females. Donyi-Polo Government College, North East Frontier Technical University (NEFTU), Boum Kakir Mission School, Government Secondary School and Tokir Vidya Niketan are some of the most reputed educational institutions in the district.
Tamiyo Taga belongs to the Bharatiya Janata Party from Arunachal Pradesh. He is a member of Arunachal Pradesh Legislative Assembly elected in present. He is the leader of Opposition in the assembly. P. K. Thungan belongs to the Indian National Congress. He is a former central minister of state for Urban Development in Government of India. He also served as chief minister during the Janata Party Government in Arunachal Pradesh Government in 1978.
The district has some famous historical and religious places which are famous not only within the country but also in the world. Some of the notable places of interest in the district are Malinithan, Akashiganga, Gompa at Mechuka and many more. Malinithan, a beautiful Hindu temple of the early medieval period is an archeological site. It is located on the northern bank of the Brahmaputra River in Arunachal Pradesh. Maa Durga is believed to be worshipped in the ruined temple in a shakti form. Akashiganga waterfall is located near the Dabaka city enclosed by a dense forest. The Gompa at Mechuka is monastery of the Mahayana sect that considered as one of the oldest monasteries. The environment of the place is very calm and peaceful.